Older hen getting picked on by younger hens. Can I put something on the places where they are pecking her? They will most likely kill her if i don't do something.
RIRs are a great breed, in a RIR flock. They tend to be the bullies of a mixed flock and can be problematic to the point that I don't recommend combining them with other breeds. Especially docile ones.
You could try some Blu-kote or similar product on pecked areas.
How many bullies and how many of the other breeds and what breeds are they?
Do you have other housing options?
1. Pinless peepers in the aggressors for two weeks and retry without. If continual bullying some have reported doing longer than two weeks.
2. Vapor rub or something similarly strong on feathers where they are picking. It tastes bad and can curb the behavior though maybe not permanently.
3. Depending on if it is one or two offenders, you can put them in to timeout in a crate or separate them for a couple of weeks. Supposedly this resets flock dynamics.
I'm not keen on bullies. I know there's flock dynamics but if a chicken was going to kill another chicken, then the aggressor would be out. Unless there's a really good reason, like the older chicken is going to die soon, or the aggressor is an integral part of a breeding program or the most consistent egg layer. If there wasn't a compelling point, the biggest bully would be gone. And then I would evaluate if the second worst bully needed to go too.
I am a new chicken keeper though so take all of this with a big grain of salt.